Increased Residence Time Research Articles

Chemical synthesis mono- and diacylglycerol from palm stearin-olein blend using continuous high shear stirred tank reactor

This research aimed to evaluate the effect of flow rate and processing time on the synthesis of high mono- and diacylglycerol (MDAG) from palm stearin-olein blend using high shear continuous stirred tank reactor (HS-CSTR). Glycerolysis-interesterification was performed at 120 ºC and flow rates of 6, 10, 14, 18, and 22 mL/min. Glycerol:oil ratio, stearin:olein ratio, NaOH concentration, and agitation rate were 1:5 (mol/mol), 60:40 (w/w), 3%, and 2000 rpm, respectively. The result showed that flow rate significantly affected MDAG concentration and the product's physical characteristics. The highest MDAG was obtained at a flow rate of 6 mL/min. MDAG concentration, slip melting point (SMP), melting point (MP), hardness, emulsion capacity, and stability were 60.36 ± 1.61%, 42.3 ± 0.01 ºC, 43.3 ± 0.06 ºC, 6.04 ± 0.32 N, 87.6 ± 1.75 % and 91.8 ± 2.99 % respectively. An increase in residence time, which means flow rate decreased, increased MDAG, SMP, MP, hardness, emulsion capacity, and stability of the product. Processing time did not significantly affect MDAG concentration and the product's physical properties. It means that acylglycerol concentrations and physical properties of the product did not fluctuate significantly during the process. Thus, it confirmed that the continuous process was stable and reached a steady state throughout the process.

Ash characterisation formed under different oxy-fuel circulating fluidized bed conditions

The CO2-intensive oil shale power industry accounts for more than 70% of the Estonian energy sector, producing large amounts of ash that are mainly landfilled. Adopting oxy-fuel technology in the Estonian energy sector, in conjunction with CO2 storage, can be a critical tool for reducing carbon footprint. Nevertheless, several differences in ash formation under oxy-fuel conditions can be expected, which can lead to additional ash handling/utilization and related environmental concerns. In this context, the composition of oil shale ash was obtained from a series of combustion experiments in a 60 kWth circulating fluidized bed (CFB) test unit under both air and oxy-fuel combustion regimes studied by means of physical, chemical analysis as quantitative X-ray diffraction and element analysis for ashes from different separation ports. During the experimental work, special attention was given to understanding the impacts of the boiler temperature, recycled flue gas (RFG), and elevated oxygen concentration. As a result, the primary goal of this research is to characterise the ash produced by oxy-fuel combustion of oil shale in order to gain a better understanding of its chemical and mineral compositions, including Ca-Mg silicates and clay minerals, as well as to investigate the behaviour of the formation of free lime and anhydrite, which are the major compounds influencing potential ash utilisation routes. The results show that although the decomposition of calcium carbonates was limited during oxy-fuel combustion because of the high CO2 partial pressure, the contents of secondary silicates and anhydrite were slightly higher. The increased particle temperature and the higher SO2 partial pressure (with RFG) can explain this. The particle size distributions (PSDs) were wider under oxy combustion, and the specific surface area (SSA) in Filter ashes were much higher under elevated inlet O2% atmosphere. Oxy-fuel combustion had no significant impact on the concentration of elements in the ash. Overall, the mineralogy of the ashes formed in air and oxy-fuel combustion environments is similar, yet slight differences exist in the formation of clay minerals in the case of increased oxygen concentrations and with the application of RFG as a result of the increased residence time of the particles.

Patient-specific fluid simulation of transcatheter mitral valve replacement in mitral annulus calcification.

Transcatheter mitral valve replacement is a promising alternative to open-heart surgery in elderly patients. Patients with severe mitral annulus calcification (MAC) are a particularly high-risk population, where postprocedural complications can have catastrophic effects. Amongst these, obstruction of the left ventricular outflow tract can lead to ventricular hypertrophic remodeling and subsequent heart failure, while subclinical valve thrombosis can result in early bioprosthetic valve failure. To elucidate the mechanisms of left ventricular outflow tract obstruction and valve thrombosis following valve-in-MAC procedures, we used image processing and Computational Fluid Dynamics (CFD) software to generate patient- and device-specific models based on preprocedural CT data. Personalized computer simulations were performed to predict the left ventricular haemodynamics after implantation in three patients with severe MAC. The simulations have successfully captured the increased pressure gradient in the left ventricular outflow tract as a result of the partial obstruction due to the implanted valve. Regions of wall shear stress above the threshold value for platelet activation were also observed on the bioprosthetic frame as a result of the reduced outflow tract area, which led to increases in flow resistance and blood residence time inside the ventricle. Consistent with these findings, areas of slow recirculating flow and blood stasis formed near the valve frame, creating potential pro-thrombotic conditions. This study provides insight into the relationship between size and shape of the outflow tract post-implantation, pressure gradients and pro-thrombotic flow metrics such as wall shear stress and blood residence time. Results show the potential of CFD modeling to bring key functional metrics into preprocedural assessment for a comprehensive evaluation of post-procedural risks beyond anatomical factors. Following further validation and extension to the atrial chamber, this approach can provide an in-depth analysis of the likelihood of valvular thrombosis.

Superporous acrylic acid and HPMC hydrogels of mefenamic acid: Formulation, characterization and optimization by central composite design.

The purpose of the study was to devise the superporous hydrogels (SPHs) of mefenamic acid (MA) to acquire the sustained action of the MA in the body. The superporous hydrogels of mefenamic acid were formulated by employing the gas blowing method. The central composite rotatable design (CCRD) was applied to optimize the effect of independent formulation factors like acrylic acid (AC), HPMC and glycerol (GLY) over dependent variables like porosity, viscosity, drug content and swelling ratio of superporous hydrogels in water, phosphate buffer (pH 6.8) and in 0.1N HCl (pH 1.2). A number of characteristics such as void fraction, surface morphology by Scanning electron microscopy (SEM) and in vitro drug release study were governed along with physico-chemical analysis by Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC) and appraised statistically by employing the ANOVA. The comparative analgesic activity of optimized superporous hydrogel formulation SPH17 was also analyzed by using tail flick method. The Fourier transform infrared spectroscopy and Differential scanning calorimetry studies approved the physical compatibility between the polymers and the drug. The Scanning electron microscopy study specified micrographic insight about the structure of formed formulations comprising presence of pores, fibers and drug-hole aggregates. The superporous hydrogels were detected to be low dense as they expressed density lower than 0.75g/cc. The decrease in concentration of the polymers and cross linker contributed towards the increase in the void fraction of the superporous hydrogel formulations. The optimized formulation SPH 17 exhibited a highly sustained release of MA for up to 10h in the both 0.1N HCl and phosphate buffer (66.6%) media. The non-fickian release of drug revealed the coupling of the diffusion and polymer relaxation mechanism of the drug release from the formulations. The obtained outcomes suggested that analgesic effect of SPH 17 was significantly (p < 0.05) higher than that of simple suspension of mefenamic acid and total analgesic effect duration for superporous hydrogel was also doubled as compared to the duration of analgesic effect produced by drug suspension. The successfully formulated SPH with HPMC K100M as a gelling agent had sustained the action of the mefenamic acid (MF) by improving its poor solubility and permeability. The introduction of inter-penetrating polymeric network (acrylic acid) using glycerol as a cross linker impart increased residence time to superporous hydrogels which ultimately enhanced the feasibility of using superporous hydrogel as oral sustained release devices particularly for gastric retention.

Hydrogen Production and Carbon Capture by Gas-Phase Methane Pyrolysis: A Feasibility Study.

Using natural gas and sustainable biogas as feed, high-temperature pyrolysis represents a potential technology for large-scale hydrogen production and simultaneous carbon capture. Further utilization of solid carbon accruing during the process (i. e., in battery industry or for metallurgy) increases the process's economic chances. This study demonstrated the feasibility of gas-phase methane pyrolysis for hydrogen production and carbon capture in an electrically heated high-temperature reactor operated between 1200 and 1600 °C under industrially relevant conditions. While hydrogen addition controlled methane conversion and suppressed the formation of undesired byproducts, an increasing residence time decreased the amount of byproducts and benefited high hydrogen yields. A temperature of 1400 °C ensured almost full methane conversion, moderate byproduct formation, and high hydrogen yield. A reaction flow analysis of the gas-phase kinetics revealed acetylene, ethylene, and benzene as the main intermediate products and precursors of carbon formation.

The effect of Si/Al ratio on local and nanoscale water diffusion in H-ZSM-5: A quasielastic neutron scattering and molecular dynamics simulation study

The dynamics of water confined in H-ZSM-5 (protonated form of the Zeolite Socony Mobil – 5) has been studied using quasielastic neutron scattering (QENS) and classical molecular dynamics simulations (MD). QENS measurements probed water confined in ZSM-5 samples with Si/Al ratios of 15, 40 and 140 at 2.8 wt% loadings. In the lower silica samples, fitting of the elastic incoherent structure factor (EISF) showed that water diffusion was confined to a sphere (with radii ranging from 3.4 to 4.3 Å), suggesting the mobile water was located within the MFI (framework type of H-ZSM-5) channel intersections, giving localised diffusion coefficients in the range of ∼0.9–1.8 × 10−9 m2s−1. In the high silica zeolite, the diffusion was observed to be far less confined and more long range in nature, with diffusion coefficients significantly higher than in the lower silica systems (∼1.8–4.8 × 10−9 m2s−1). MD simulations further investigated the effect of the Si/Al ratio on water diffusivity at 2.8 wt% loading (9 molecules/unit cell (UC)) in H-ZSM-5 with Si/Al ratio = 15, 47, 95 and fully siliceous. The Si/Al ratio had a significant effect on the MD calculated nanoscale diffusivity of water, reducing the self-diffusion coefficient by a factor of 2 from a fully siliceous system to that with Si/Al = 15, due to the strong coordination and increased residence time of water molecules at the Brønsted acid sites which range from ∼5 ps to ∼2 ps in the Si/Al = 15 and Si/Al = 95 systems respectively. QENS observables, both the EISF and quasielastic line broadenings, were reproduced from the MD trajectories upon sampling the experimental timescale giving both qualitative and quantitative agreement with the QENS experiments. Fitting of the MD calculated EISF showed that the experimentally observed diffusion confined to a sphere of radii ranging from 3.5 to 6.8 Å was also present in our simulations, with diffusion coefficients calculated to within a factor of 0.5 of experiment.

High Molecular Weight Fucoidan Loading Into and Release from Hyaluronate‐Based Prefabricated Hydrogel and its Nanogel Particles Controlled by Variable Pitch and Differential Extensional Shear Technology of Advanced Twin Screw‐Based System

AbstractEfficient incorporation of high molecular weight drug into prefabricated hydrogel and its delivery are big challenges in its applications to drug delivery and tissue regeneration using a 3D bioprinting system. In this work, a new method of loading a model high molecular weight drug (fucoidan with 200 kDa) into prefabricated hyaluronate‐based terpolymeric gel is developed by using an advanced screw‐based extrusion printing system. This system effectively incorporates the fucoidan biomolecules into the prefabricated crosslinked gel within 60 s at significantly higher percentages without much change in gel properties. Less damage in gel network is achieved through variable pitch and differential extensional shear mechanism by optimization of bioprinting conditions. Importantly, fucoidan‐loaded nanoparticles (NPs) are developed using the advanced extrusion system at high screw rpm and with increased residence time using recirculation. The encapsulation efficiency, sustained release of fucoidan, and in vitro cell culture studies confirm the nontoxic nature of the drug‐loaded gels and nanogels at lower doses, exhibiting the biomedical application potentials of this advanced screw‐based extrusion printing system and drug‐loaded NPs formation in pharmaceuticals, 3D bioprinting, tissue engineering as well as maximal drug loading into and sustained release from prefabricated gels.

Incorporating hydrothermal liquefaction into wastewater treatment – Part II: Characterization, environmental impacts, and potential applications of hydrochar

Hydrothermal liquefaction (HTL) is a promising technique for renewable biofuel (biocrude) production from municipal sludge. However, its solid byproduct, hydrochar, requires sustainable management for further resource recovery and pollution control. This study comprehensively assessed the properties, environmental influences, and possible utilizations of hydrochar generated from mixed sludge (MS). With the increase of HTL reaction temperatures (290–360 °C) and residence time (0–30 min), the dry-weight contents of ash and fuel ratio increased from 10.5% and 0.1 in MS to 48.7–68.5% and 0.4–0.7 in hydrochar, respectively. However, the dry-basis contents of volatile matter, carbon, and higher heating value sharply decreased to 18.7–35.9%, 22.9–37.3%, and 8.6–16.0 MJ/kg, respectively. The leaching risks of inorganic contaminants from hydrochar were limited and controllable in various scenarios. Hydrochar performed more stable combustion than sludge, but its high ash contents and alkali index (0.28–0.72 kg/GJ) implied high risks of slagging and fouling. Hydrochar has a good potential for carbon sequestration due to low O/C ratios (<0.2) and improved recalcitrance index (0.43–0.48). Benefiting from intrinsic metals (e.g., Ca and Fe), catalytic hydrochar graphitization was feasible at a moderate temperature (1200 °C). Although hydrochar was restricted from land application for heavy metals accumulation, it is promising for metals and nutrient recovery. It has a total phosphorus (P) of 7.2–8.5% by weight, and thus P recovery is critical and necessary for mitigating environmental challenges and global P scarcity. Overall, this study contributed to the state-of-the-art in waste-to-resource development and cleaner production.

Effect of water quality ununiformity on production of marine medaka

The large amount of organic impurities deposited at the bottom of an intensive aquaculture pond often leads to the deterioration of the surrounding environment, creating additional environmental stresses on the farmed fish and affecting its growth. This study investigated the effect of water quality ununiformity on growth, feeding behavior, and stress tolerance of marine medaka (Oryzias melastigma) through differences of residence time in different water quality areas in the same aquaculture system. Through the pre-test, the flow field distribution in the aquarium for cultured experiment was clarified, and the water body in the aquarium was divided into the central area (Ce) and the corner area (Co) according to the water quality difference in different flow fields. Then, seven residence time gradients were set in Co, which were 24 h, 14.4 h, 7.2 h, 4.8 h, 2.4 h, and 0 h, respectively. That was, they accounted for 100% (P100), 60% (P60), 30% (P30), 20% (P20), 10% (P10), and 0% (P0) of a whole day, respectively. The results showed that, all water quality indicators such as dissolved oxygen (DO), pH, nitrite (NO2−-N) and non-ionic ammonia (NH3−N) in Ce and Co were consistent with the requirements of the standard (GB11607–89) during the 28-day cultured experiment, but the water quality in Co was gradually worse than that in Ce, with the prolonging cultured period. In spite of increasing the body length and body weight of medaka in all treatments, their growth rates had significant differences among several treatments (P0 = P10 = P20 > P30 > P60 = P100). And the fish's growth, feeding efficiency, and stress resistance decreased with the increase of residence time in Co (P < 0.05). Through nonlinear regression analysis, it was predicted that the accumulation of residence time of marine medaka stayed in the coner area was >6.667 h, its feeding behavior would be affected, and the corresponding appetite and food intake, immunity to disease and growth rate would all decreased. Attaining uniformity of water quality in aquaculture system may help improve fish welfare and increase the sustainability of aquaculture.

Loss of reef roughness increases residence time on an idealized coral reef

Through idealized, numerical models this paper investigates flows on a reef geometry which has received significant attention in the literature; a shallow, fringing reef with deeper, shore-ward pools or lagoons. Given identical model geometries and varying only reef flat drag coefficients between model runs (C_D = [0.001,0.005,0.01,0.05,0.1]), two distinct circulation patterns emerge. One is related to low reef water levels and high roughness, and efficiently flushes the entire reef system resulting in low residence times (an ‘open reef’). The other is related to high reef water levels and low roughness, and in spite of the development of an offshore undertow, this dynamic is inefficient at flushing the reef-pool system and facilitating exchange flow with offshore waters (a ‘closed reef’). This paper shows that even given indistinguishable geometry and offshore conditions, this information is insufficient to predict reef dynamics, and suggests that reef roughness (and thus reef health) plays a comparable role in determining circulation patterns and residence times. Furthermore, a transition from open to closed or vice versa caused by e.g., a loss of reef roughness or increase in mean sea level could have implications for transport and mixing of nutrients and water masses, as well as larval dispersal.

Combination of oscillatory and hydrodynamic system for biodiesel production from sunflower oil

In recent years, biodiesel as renewable energy has attracted much attention. The major aims of the biodiesel production method are high conversion and reduced reaction time. This study aimed to optimize biodiesel production from sunflower oil using the transesterification method in oscillatory-hydrodynamic combined systems. The dimensions of the smooth periodic constriction reactor (SPC), tube diameter (D), the diameter of constricted area (d0), and baffle spacing (l) were obtained at 5, 2, and 13 mm, respectively. The process optimization was carried out by response surface methodology. The results indicated that by increasing residence time from 30 s to 90 s, the yield was increased about 6%. By increasing the catalyst concentration from 0.75% to 1%, the yield increased approximately 6%; increasing the molar ratio from 6:1 to 9:1 increases the yield. The yield was also increased with the reaction temperature rise from 30 °C to 40 °C. Then, by increasing the temperature from 40 °C to 50 °C, the methyl ester content was increased from 81.59% to 85.75%. The optimum point was tested and compared with the ASTM D6751 standard. The results showed that transesterification of sunflower oil with this combined system could function as a good alternative to diesel.

Numerical and experimental investigation of a lighthouse tip drainage cannula used in extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation is a life-saving therapy used in case of acute respiratory/circulatory failure. Exposure of blood to non-physiological surfaces and high shear stresses is related to hemolytic damage and platelet activation. A detailed knowledge of the fluid dynamics of the components under different scenarios is thus paramount to assess the thrombogenicity of the circuit. An investigation of the flow structures developing in a conventional lighthouse tip (single-staged) drainage cannula was performed with cross-validated computational fluid dynamics and particle image velocimetry. The aim was to quantify the variation in drainage performance and stress levels induced by different fluid models, hematocrit and vessel-to-cannula flow rate ratios. The results showed that the 90° bends of the flow through the side holes created a recirculation zone inside the cannula which increased residence time. Flow structures resembling a jet in a crossflow were also observed. The use of different hematocrits did not significantly affect drainage performances. The most proximal set of holes drained the largest fraction of fluid. However, different flow rate ratios altered the flow rate drained through the tip. The use of 2D data led to a 50% underestimation of shear rate levels. In the drainage zone the non-Newtonian behavior of blood was less relevant. The most proximal holes drained the largest amount of fluid. The flow features and distribution of flow rates among the holes showed little dependence on the hematocrit. The non-Newtonian behavior of blood had a small influence on the dynamics of the flow.

Sediment oxygen demand rate in a flow regulated lagoon (Venice, Italy)

From October 2020, the MOSE system went into operation in the three inlets to protect Venice and its lagoon from flooding caused by high tide events in the Adriatic Sea. While the MOSE increases the prospect of physical defense, how will the new status of a regulated lagoon affect the functioning of the waterbody? In particular, the dissolved oxygen balance in the water column can be affected by the expected increase in water residence times. Sediments play an important role in oxygen consumption in the water column and for this reason sediment oxygen demand (SOD) was studied in situ for the first time, in 16 sites at four lagoon areas. SOD rate, measured throughout 2021 with specially made benthic chambers, varied in the different areas and with seasons (from 0.63 to 24.00 g m−2 d−1), with higher values at the more confined sites and significantly lower values in those belonging to the open lagoon. Based on SOD rate, consumption times of dissolved oxygen in the water column were estimated at the MOSE closures, from saturation values to hypoxia and in the temperature range of 11.7–33.3°C. Especially in the confined sites, sediments can exert an important depleting action on dissolved oxygen already at water temperatures above 20°C, which are not particularly high for the lagoon.

Sono-Enzymatically Embedded Antibacterial Silver-Lignin Nanoparticles on Cork Filter Material for Water Disinfection.

Providing clean drinking water is a great challenge worldwide, especially for low-income countries where the access to safe water is limited. During the last decade, new biotechnological approaches have been explored to improve water management. Among them, the use of antimicrobial nanoparticles for designing innovative centralized and decentralized (point-of-use) water treatment systems for microbial decontamination has received considerable attention. Herein, antimicrobial lignin capped silver nanoparticles (AgLNP) were embedded on residual cork pieces using high-intensity ultrasound coupled with laccase-mediated grafting to obtain biofunctionalized nanomaterial. The developed AgLNP-coated cork proved to be highly efficient to drastically reduce the number of viable Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in liquid medium. Additionally, the coated-cork was characterized using FTIR-ATR spectroscopy and SEM imaging, and further used as a filter bed in a point-of-use device for water disinfection. The constructed water filtering system significantly reduced the amount of viable E. coli and resistant Bacillus cereus spores from filtered water operating at increasing residence times of 1, 4, 6, 16, 24, and 48 h. Therefore, the presented results prove that the obtained cork-based antimicrobial nanocomposite material could be used as a filtering medium for the development of water filtration system to control pathogen dissemination.

Anti-depression effectiveness of essential oil from the fruits of Zanthoxylum bungeanum maxim. on chronic unpredictable mild stress-induced depression behavior in mice.

The fruits of Zanthoxylum bungeanum Maxim. Was a popular traditional Chinese herbal medicine for pain relief, itching prevention, and diarrhea relief. The fruits of Zanthoxylum bungeanum Maxim. Essential oil (HEO) had an effect of improving anxiety and other emotional disorders. In this paper, we aim to systematically research the antidepressant effects of HEO on Chronic Mild Unpredictable Stimulation (CUMS) mice and explore the relevant molecular mechanisms. Experimental mice were exposed to CUMS for 8 weeks. Meanwhile, for 8 weeks, Sertraline hydrochloride (20 mg/kg/day) and HEO (50, 100, and 150 mg/kg/day) were administered by gavage. HEO treatment increased residence time of central zone in OFT and open-arm in EPM test but decreased immobility times in FST and TST. Moreover, HEO treatment improved the levels of 5-HT, DA, NE, and BDNF, but reduced CRF and CORT levels of the HPA axis in the hippocampus. Network pharmacology predicted the possible mechanisms for the antidepressant effects of HEO by regulation of PI3K/Akt signaling pathway. The mRNA expression of PI3K and Akt were increased, and immunofluorescence results in the hippocampus indicated that HEO treatment could increase the phosphorylation of PI3K and Akt. Besides, the viability of CORT-treated PC12 cells was significantly improved by HEO treatment. The AO-EB staining, MOMP analysis, and flow cytometry analysis results showed HEO inhibiting the CORT-induced apoptosis in PC12 cells significantly. Besides, the phosphorylation of PI3K and Akt in COTR-induced PC12 cells could increase by HEO treatment. In conclusion, HEO ameliorated depression behavior induced by CUMS, potentially via regulating HPA axis and activating PI3K/Akt signaling pathway to reduce neuronal apoptosis.

Impact of barrages on assemblage pattern of phytoplankton in tropical river Ganga, India.

The occurrence, abundance, and distribution of phytoplankton have been investigated upstream and downstream of three barrages on the river Ganga at Bijnor, Narora, and Kanpur in Uttar Pradesh, India. A total of 104 phytoplankton species belonging to eight phyla (Bacillariophyta, Charophyta, Chlorophyta, Cryptophyta, Cyanophyta, Euglenophyta, Miozoa, and Ochrophyta) were identified during the sampling period. During the summer, monsoon, and post-monsoon seasons, the density of phytoplankton (Ind. L−1) ranged from 9.6 × 104 to 2.03 × 107, 9.6 × 104 to 4.5 × 105, and 2.2 × 105 to 2.17 × 106, respectively. The species abundance and the relative abundance showed an increasing trend from the first (Bijnor) to the third (Kanpur) barrage, suggesting a gradual decrease in river flow and an increase in residence time. Phytoplankton cell density in Kanpur, however, was unexpectedly higher and showed eutrophic conditions attributable to elevated organic load and surplus nutrients from the land runoff. One-way ANOVA (post-hoc Tukey test) showed statistically significant (p < 0.05) seasonal variation in temperature, transparency, free CO2, PO43−, and dissolved organic matter. Analysis of Pearson’s correlation coefficient suggested a statistically significant correlation (p < 0.05) of mostly phytoplanktonic groups with free CO2, CO32−, HCO3−, Cl−, specific conductivity, total dissolved solids, total hardness, Mg2+, PO43−, and SiO44−. The minimum species diversity was recorded during the monsoon season, while the maximum diversity was reported during the post-monsoon season which might be due to high nutrient load and a high concentration of PO43− post-monsoon. We concluded that aquatic biodiversity and ecological structure could be adversely influenced by a series of obstructed barrages and dams, which influenced the assemblage pattern of phytoplankton communities.

An Overview of Nanostructured Lipid Carriers and its Application in Drug Delivery through Different Routes.

Nanostructured Lipid Carriers (NLC) are nano-sized colloidal drug delivery system that contains a lipid mixture consisting of both solid and liquid lipids in their core. This Lipid-Based Nanosystem is introduced as a biocompatible, non-toxic, and safe nano-drug delivery system as compared to polymeric or metallic nanoparticles. Due to its safety, stability, and high drug loading capacity compared to other lipid-based nanocarriers, NLC gained the attention of researchers to formulate safe and effective drug carriers. The ability to increase drug solubility and permeability while encapsulating the drug in a lipidic shell makes them an ideal carrier for drug delivery through difficult-to-achieve routes. Surface modification of NLC and the use of various additives result in drug targeting and increased residence time. With such qualities, NLCs can be used to treat a variety of diseases such as cancer, infections, neurodegenerative diseases, hypertension, diabetes, and pain management. This review focuses on the recent developments being made to deliver the drugs and genes through different routes via these nanocarriers. Here, we also discuss about historical background, structure, types of NLC and commonly employed techniques for manufacturing lipid-based nanocarriers.

Highly sensitive detection of polystyrene by on-line splitless pyrolysis-gas chromatography/mass spectrometry with cryo-trapping of pyrolyzates and forced venting of carrier gas

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) has been extensively used as a powerful tool for polymer analysis. In Py-GC/MS measurements, GC methods have usually employed split injection conditions for qualitative and quantitative analysis, but splitless injection of pyrolyzates to GC/MS has been reported to obtain higher sensitivity for small amount of analytes, since split ratio is inversely related to the amount of analyte entering the detection systems. However, the slower total carrier gas flow rate of splitless injection, which is necessary to keep the column flow rate at around a few mL/min, can increase residence time in the pyrolysis chamber, which can cause unfavorable secondary reactions of pyrolyzates such as decomposition and recombination in the pyrolyzer. In this study, we developed a new on-line splitless Py-GC/MS method called the Forced-Venting-and-Trap-Splitless (F-Splitless) method, based on cryo-trapping of pyrolyzates and forced venting of carrier gas under high carrier gas flow rate. Calibration curves measured by the F-Splitless method for polystyrene (PS) using the styrene monomer and trimer as key compounds show a good linearity over the concentration range from 0.01 ng to 100 ng. Limit of detection (LOD) and limit of quantification (LOQ) were 17 pg and 56 pg for the styrene monomer (S) based on the criterion of LOD: 3σ/a and LOQ: 10σ/a, where a is the slope of the calibration curve and σ is the standard deviation of the peak area of the minimum concentration, using the selected ion monitoring (SIM) mode. At a trace concentration level of PS, contamination from the environment was recognized. However, 100 pg of PS showed a signal to noise ratio (S/N) of 570 for S in SIM mode and 1.8 pg of PS could be quantified according to the criterion of LOQ based on signal to noise ratio (S/N), i.e., S/N = 10.

Improvement of deposition characteristics of silicon oxide layers using argon-based atmospheric-pressure very high-frequency plasma

We have investigated the deposition characteristics of silicon oxide (SiOx) layers in atmospheric pressure (AP) argon (Ar)-based plasma at a substrate temperature of 120 °C. A 150 MHz, very high-frequency (VHF) power is effectively used for exciting stable and uniform hexamethyldisiloxane (HMDSO)-oxygen (O2) fed plasma under AP. The microstructure of the SiOx layers is discussed in comparison with that by using helium (He)-based plasma. In the case of depositions with He/HMDSO/O2 plasma, SiO2-like films with uniform thickness, which have sufficient compactness to be used as the gate dielectrics of bottom-gate thin film transistors, can be obtained by moving substrate at a constant speed during the plasma operation. However, the decrease in the total gas flow rate (increase in the gas residence time in the plasma) causes the increase in the participation of nanoparticles to the film growth, which might result in the deterioration of film quality. Shortening the electrode length is effective for avoiding the incorporation of nanoparticles into the growing SiOx films. On the other hand, when Ar/HMDSO/O2 plasma is used, no deterioration of film compactness is observed irrespective of the gas flow rate. The results obtained in this study demonstrate the effectiveness of the VHF excitation of AP plasma on the generation of stable and uniform glow discharge without using He, which will lead to the development of a highly efficient and reduced cost formation process of good-quality SiOx films.

Effects of residence time on the NOx emissions of premixed ammonia-methane-air swirling flames at elevated pressure

In this study, a bespoke single-stage swirl burner was used to experimentally investigate the effects of residence time on emissions from premixed ammonia-methane-air flames. The residence time was altered in two ways: by modifying the combustion chamber's length or by modifying the swirl number. Exhaust emissions of O2, CO2, CO, NO, NO2, and N2O were measured at an absolute pressure of 2 bar for equivalence ratios between 0.50 and 0.95 and ammonia fractions in the fuel blend between 0 and 100%. Spatial distributions of NO and OH radicals were also imaged using PLIF inside the combustion chamber at different heights above the nozzle. Data shows that increasing residence time can further advance chemical reactions, as evidenced by a reduction in O2 concentration in the exhaust. Increasing the swirl number reduces emissions of NO, NO2, and N2O more efficiently than tripling the chamber's length. However, a decrease in the combustion efficiency may be responsible for a fraction of this NOx reduction when the swirl number is increased for some equivalence ratios. NO emissions are not modified when the chamber's length is increased, which is consistent with the fact that the NO-LIF signal does not decay when the distance from the nozzle increases. Therefore, NO formation is somehow restricted to within the main reaction zone of the swirling flame, that is, the zone whose height does not exceed 60 mm for this burner. Conversely, tripling the chamber's length reduces the concentrations of NO2 and N2O. This reduction is not reflected in a measurable increase in NO concentration because NO is present in much larger quantities than NO2 and N2O in flames examined here. Consistent with the fact that OH promotes NO formation via fuel-NOx pathways, a positive correlation is found between NO- and OH-LIF intensities.